1. Field of the Invention
The present invention relates to a double-acting or lift and force pump for ejecting a product from a container, with a housing in which a piston with an axial bore is axially slideable and sealed by a first housing portion, with a hollow piston rod which extends the axial bore of the piston and is slideable in an opening of a closing cap of the housing and container, wherein the hollow piston rod has at its free end a tightly fastened actuating head, wherein, when the actuating head is actuated, the actuating head presses the piston against the force of a restoring spring toward a connecting pipe portion for an immersion pipe provided in the housing, so that a pressure is built up in a pressure chamber of the housing which presses a first valve closing piece in the connecting pipe piece against a first valve seat, wherein an outlet duct connected to the bore extends through the actuating head and through a check valve up to an ejection opening for the product, and with at least one opening in a second housing portion between the first housing portion and the closing cap.
2. Description of the Related Art
In a double-acting pump of this type disclosed in DE 27 09 796 B2, the product can be suctioned from the container and can be ejected by a pressure stroke when the pump is in the normal upright position in which the actuating head is located higher than the connecting pipe piece. However, in the inverted position, i.e., the upside down position, the product could not be ejected out of the container as soon as the filling level in the container is in the upside position lower than the suction opening of the immersion pipe, which is also called ejection pipe. The product ejection would be possible in this upside down position only if a suction stroke has been carried out previously in the normal position.
Therefore, it is the primary object of the present invention to provide a double-acting pump of the above-described type in which the products can be suctioned from the container and dispensed from the container even in an upside down position in which a filling level of the product in the container is lower than the suction opening of the immersion pipe.
In accordance with the present invention, in the non-actuated state, the piston releases as a result of the restoring force of the spring a passage between the pressure chamber and the at least one opening in the second housing portion, wherein the connecting pipe piece has a second valve seat and a second valve closing piece which, in a position of the double-acting pump in which the actuating head is lower than the connecting pipe piece, the second valve closing piece assumes its closing position at the second valve seat, and the second valve closing piece assumes its open position in an inverted position in which the actuating head is higher than the connecting pipe piece.
In this solution according to the present invention, in an upside down position of the pump, the product is suctioned into the pressure chamber during the suction stroke of the pump through the opening or openings in the housing wall and the passage, and the product is ejected during the pressing stroke. Accordingly, the double-acting pump can suction and dispense the product in the upright position of the pump as well as in the upside down position of the pump.
In accordance with a preferred feature, the passage is formed by at least one axial nut in the inner side of a middle housing portion between the first and second housing portions.
Also, the second valve closing piece may be actuatable by its own weight.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.